1. Field of the Invention
The present invention relates to a method of manufacturing semiconductor devices, and more particularly, a method of manufacturing semiconductor devices capable of prohibiting charge loss within a tunnel oxide film and improving a retention characteristic of the flash memory device, by prohibiting a phenomenon that hydrogen contained in a spacer oxide film is inter-diffused into the tunnel oxide film.
2. Background of the Related Art
A retention characteristic in the flash memory device has great influence on reliability characteristic of the device. A material for use in the spacer in the flash memory device includes high temperature oxide (HTO) using SiH2Cl2 (dichlorosilane; DCS) and a Si2H2Cl2 gas is used as a source gas. Thus, hydrogen exists within the spacer. In other words, hydrogen is trapped within the spacer oxide film according to the following [Reactive Equation 1].SiH2Cl2(DCS)+O2→SiO2+H2+Cl  [Reactive Equation 1]
Also, as annealing is implemented within the furnace for a long period of time, hydrogen can be easily inter-diffused. In other words, as high temperature oxide (HTO) using SiH2Cl2 (DCS) is used as the material for the spacer, hydrogen contained in the Si2H2Cl2 gas is contained within the spacer oxide film. Thereafter, as the high temperature annealing process proceeds, hydrogen left within the spacer oxide film is inter-diffused into the tunnel oxide film. As such, hydrogen ion existing within the tunnel oxide film forms a Si—H bonding. In a program or erase operation, electrons are neutralized by the hydrogen ion. In the result, charge loss occurs. This charge loss results in degradation of the retention characteristic in the flash memory device.